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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bf31e65a3f8b59caedd99258677864d3b0b210378a8f57a1750a77a42e77ea0c' 
  AND token = '8zTXFzN5ZKhZ0cRXvXD+Nt53CzFn/fY/kw3kTv/uzgY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}