SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e2c7d7d083278085395c63770eb9a3956961a2934fd69568c30912280b4e8bef' 
  AND token = 'tGGc7SKmMU8PC1RQd5B+y+aYB+FgFvA0xTfRLVVKpO4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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