SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2a276d211fdaf1c19134301a6d2425a499d28e9c9315181cc22a92fb112f37bd' 
  AND token = 'k911Tn3GgHST45l2Mb7hH77L7J3Bm7LDGQpKaDMywzk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}