SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '6b0962ed67c5c4fec7ec0225e17c2889942588ede0b5aa52efa78e0576a94da7' 
  AND token = 'q/Rfv0TMmMahzVC/eZEqKh3/gfQS9HyYw4n2Wb/fQ/w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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