SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f9413a1791cb28ed6b32503f3e6d8ce8d0ecdd5b617e6a359c8473723aeabed9' 
  AND token = 'PSar+Dc6yFV0vnZ5t0xTaY3kc0ESRnM6k8pvIPpwLKU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}