SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b772be595fc1b7276b842cef1589e252f204378cc58ded7343b13ad70582e108' 
  AND token = 'mB2hPBcoMOhaONH79iAJvYq8UwYea5iNFMA7sbyg15M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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