SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd354ca24e3640295bc971ad2529f3530c3443ec48fe525753acc9c21d43ece02' 
  AND token = 'R2cGJu8txyoemkaERYMOaO2eQMy6ATfczIzt+kUrJIU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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