SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bcd3eb22f8a397ed401fc98fe975a56fd635eb079d6ca122265407e54d1a0410' 
  AND token = '/KOmgJEnsOc991beXcZ1hRXIL9nBONzHXxiSGB77h+I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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