SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '48ca6b794e6d621fe73ca3eeb297d1e37ff1053ba6503432c34f1ded877ec524' 
  AND token = 'fOx6kWbaur2wIBhbqusjMIR07M9Wk7sB2fVRVU2heAg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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