SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '38c1c55b370e92588dd1111524480227e7131aa015f1581b9954bfa5543200b1' 
  AND token = '0LdIMZTtbR8arz4UZINxjaBzjoijwpg02a+s/Tv5Qwc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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