SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '823553ebf31e0802785d8015198c9751e088a9ffe6f0ad59f2622445c273fa2c' 
  AND token = 'z37kguZJXLjU7Q20J4Beg3qIfuHfuJk23KrDzrWwBFE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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