SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6cf714b511212dd20c0e8bb9bef3936754b969457c428f8ffee7866d4a029442' 
  AND token = 'b0C4Ojosgo8o6/JWdhk1zOTEPL+LRrxhsQ/p+3KnOuA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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