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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '78c49dad5f4efc546e08b528fcb6ff7b520ebaae77e1821cadd09bcd9b9e80bf' 
  AND token = 'HTkA1aaPqa2sXKzTG5TUMz35PsrhfpiBXQWO4Qk4kYg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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