SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4c50a0baeb8313f3b8f07623725df7adb9a125be43910973bbf39c44973472fd' 
  AND token = 'fxzQ1RiEFiJCv2Hs0ZDYfxj+BuU6WoKwGhBvFR80kt4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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