SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '603f58318091c3c635c56dcf99f52649f22a644be1e774bbfc8001d166c6a7a3' 
  AND token = 'Q1OyaUnNHeBHigkfvQ998bpQwRpmPXDJvoSYfobSq1w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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