SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '918882825a9becb78dfb66cad50d7b081713d07ceebacc7e713b6f97a8be5939' 
  AND token = 'JS5vLz37NmuCyEIwP/PcNPu0lZjizuZwZWFSrbBA74Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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