SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '951be6a4be00c287aa909778afed916f49551d7e113117d041231265f9064d3a' 
  AND token = '56EpXin4byVWjzLTbBQb17vHveaz7IfScwmhtemKg50=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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