SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1686cb4846eedde10bddaf0697200e08d6712c520776eb98ea2e7eeb2055fd27' 
  AND token = 'aAF23pq2Vxc3EAWRPbKf1+uLUJ0AVwlTAfVJwt+3mzg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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