SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a1a9943cd8532c5fea12189e005e3989e42cb8f38763351cd424817dd9a79349' 
  AND token = 'McShHGnQfCnn+wnEpV3Ww3z/rvCDvDqNLqBAqZJqOKU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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