SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '257a9d14231efbba6c3bb54294827aec8c9bad16a78b259039bf5a78fc7baa9c' 
  AND token = 'wiHk9ivCNODuogDXhrtrEE/p2xYjcETyXcC37FClEy8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00045

JSON explain

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