SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5431ef1f8616793f089fa3b25177bd436e850a22b02c55e9517708a7a52f9eeb' 
  AND token = '+x3i6sz4BqN061tGWvtJgawpM1lTDYd8uhgeIyVD9mY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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