SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3b96657935b5e6859cd6cda992ed71bca2fa9c36968555149b796d8ffa02d7c7' 
  AND token = 'jzoMrjMj+mtiJaAuqpskEfCiwzdlYJhC3nhOEkbMfyg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

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