SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fb92c36680cd018d468d9a51998da75da64bb61aca61babb4696c1086db239e7' 
  AND token = 'cIKgNZof2MmasnE4mt/zAiWzS8o32ZNJJTAjSCqzH10=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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