SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fb0d306bc780ff6bb0a8a20a6c55e91399829aadfa517d273908200a2cc5c38d' 
  AND token = '7CuXwp0iPbnIWBSoYRtu6WbAeDoO6tuAK0Cug6BsvDw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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