SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a72d1b57090d53469a77fef98bbf30881c46f738ceec93245c35ead8a94f3aa4' 
  AND token = '19GCxUKSD1RKY2Z5ufMoqmgDiBh4Wy/HGjsofJRrh6A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00054

JSON explain

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