SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '52bd2a367894052f8a41e1621d923fc12c21400299920986cbbe8f7e85222316' 
  AND token = 'j35nR1rTPPIdUClNbLvQGvq+SGUpWUozZ/QxzDbJ7pE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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