SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8c9def2822e1ba3ff88cea596cdb3435790c567ff693b32ad1bf2f6525f3744d' 
  AND token = 'Zr0TdJD+wGDI1j8yYOQPuWMxaRCrQW7ZKQeFtbAg56Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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