SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a7bb13d51685f17515be40831185ad4c6558c791d65da9b660af528734023521' 
  AND token = '5eiHEWQS2tSc+A0VzzoQBJhZcB53si1wD0UmDdu2y0I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00048

JSON explain

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