SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2d5befcdee20ffd733f2239e31604f8c0da249ab551e027568023df77520da1c' 
  AND token = 'tSufMW0+9MSdu6Xuve8OmPU8zSVOnzPTwL9M5w7nR/E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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