SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e3aacad1022172c65942ca0c2c683938f562cdfe9c671bb2caceffe8d4c3aa6a' 
  AND token = 'kagy0o1rHLCRWU1M3JlNDEjqZbEHhVEn06WVA8ji+Wo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00051

JSON explain

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