SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5710f17018ff34dbff37f5a379d29e2628ae051b125ca2124dcc2cbb6531b599' 
  AND token = 'lgq6T/PkiteWNCb8kwpfl65vhvhwy0EP0Y/1yWYHMQk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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