SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b64abbb8bd3d186fc8585212bcdaec00b76129ea2327d10ff4c946182951416a' 
  AND token = 'dlTvXW6EMn7rlggOh7pvLHAHlyaVBZnVCmt+xxg6E0c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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