SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a9abe51c62c0ddb9164b34fc6e079af36deb607f3ad31220920508a5e22cc700' 
  AND token = 'glABh6f9oGFDeCeSgsDhlK2xeOmk/LXUSx/87uzPiII=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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