SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '15e873da0eb548340303f5c52092fdcbd9b6446b9946f6bcdc00ef5cb577270e' 
  AND token = 'j352kHZky1oL56c6zgFtPWJPHh35hEHK3zLJ34ylnjE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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