SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '97f5418282fe9306f1362062cd2c033a2b91bc8f82202bad6b9c8b08af0cc87e' 
  AND token = 'EXLtfis+7EZHCyh69tLI45LODHTcXptOw9oHrrPPckc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}