SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '23b420151556727711a16f22a1eb2336d5daf00433fdfc5db6c436943f8dfbfb' 
  AND token = 'OYZrQC4kR5VaSIy8+lEJ/lw8VEUzXpEm4haWS9Lw/QM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00064

JSON explain

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