SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f552b714928f0d7e64499500e9168e198c7e9a763380892c7f68d4ec42cae89c' 
  AND token = 'cs4lR3vUrZgNITHQaa5BNI+dXQNGN1dP8BqTjt+gc3c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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