SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8138a23413a95e0f02657ca1286b39c51ffaf9c0240430f5ef03f98b642b2eb1' 
  AND token = 'mAbF6QKgdcv8cswynRIJfrFg3EVn4byNoUkilLLvxRc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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