SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '03998eb6111f4616dc3bc2649df275feef95b7f3a78268f5eb01e9926cb3358a' 
  AND token = '6ZMQ94tBVAv0hYzmXA/RQCrEd9K5vsN+CxwsE3yAzXA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00055

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}