SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a0e61677cbd952e634cf226825c1fe1059bee54eb17328bf1ba945d43c1505c8' 
  AND token = '9MEsvAL29F4JEajU73oe2VgKOquie4o31NJNeFqmmoQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00053

JSON explain

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