SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a76e8d87cbe896a2dbd7a0bc7e6429bdc0b210465824e60b7fa82f436e446319' 
  AND token = 'wZj5VLzKdQPlzLENPAs7dZKz/audNSvJD+L8RtIr3nQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00015

JSON explain

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