SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '51706bd7ba2018859f95f398cbce93c74fcd0d7fac56637fc832bb0eca277326' 
  AND token = 'M7VPNR5eBQeJxbW0+QKCEsVNkQfueKinsVKeQvJ2whw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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