SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '49a8ae0bdbc264c0241433843832164fb701b14fa813c677700d29967ca3c1d5' 
  AND token = 'ub+qg5MLVovZLO+SKVib0wc6QQU2wwQqCUJoDtLo9uI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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