SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a8f85cd7073ac0727ac4e6ff4b275fad15421c235dce2293f8541f863b468571' 
  AND token = 'CPAuVeBBqB2rb+lzESm09WHbSZpCZAWNJBMDRiFi9Io=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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