SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2a236cba03c902a87c6ad4b76d8ea16c15e800861ad983c4f0480d966c8ccbee' 
  AND token = 'q6dzEVFJPr+ZSoMlAsHSVtgReYsA/o3AiT8JLDqlfxo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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