SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b553708c8ac587ef216c40341fef949a83d1018f4c86d7d6aa5600e6ab6d2ade' 
  AND token = 'mFo/GB4wJwD3yznC1K1V2BVHZOKq+ANu/SAEZo1rdQY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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