SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '49b6556407cdf92311b632a2c87bde76de8e38dee432a2f5d3895f25097efa2d' 
  AND token = '1l6uYVWQNduMyxrwXZI0+JYRRyEvLg83OvrVLJR/bBU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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