SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7bcd3e8aba0ad9b16141b64d3d63d1270c89921806163460f112e654927b2fb8' 
  AND token = '9j8ELtZYMMNIeqQsjKmRf4QQqExSZrRuSYOCpEuqH3Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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