SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8a99416397c6bd549671171deabc86c52e078c9b05422d26d4902599a376f2b5' 
  AND token = '5HowKCtG7qcMXntyhIT3nvAIwImRLBSERm03L+x8JmU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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