SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a66e96670fbc83486fa1a5a835136a08e97a915cd47e31775105fa5f58b3e27c' 
  AND token = 'OzjW3e47v55Yceb9E6jjuODFD2mp58v8I+BMMF/zzNE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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