SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '71645a6a25cec65d56b5729b10324bfe72582ed4955b70748a389451e3ebe502' 
  AND token = 'ESDIgfYzYJJw+P9CXCykwBarkDP3MuOSsJUmpTwWgEs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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