SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b7a5c900df1300cb2aeb3072ced341b028dedc0de4e05ff585412d79536453a2' 
  AND token = 'u2LSvuHjlbLiXvwOm4pfgqA1AgJ1Vh7xBPbjKkW+ARU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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