SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b87f0607064b487ff25a8148be3b9471688849d437cb472164203879d471132f' 
  AND token = 'NK2sfJ2bFO74JasWktgGwbYOH3RKzuSO6MT2iHbFpQk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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