SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '81a7a1111c533f5c043ddcb41a0cc43ef77750625d10f88860af0093a713c069' 
  AND token = '9XFdUJ1BKoBlPmDz1THgrv16QagsYn+OIbEg6BYV+fw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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