SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ac7ac83e2031531c16f97b4283ac283add3db30ec5592c2bc2b35c87027427c0' 
  AND token = '9LpRXNT4dnZHbJQXOq40mCsKzFIjFxy+VRCOHFzzRdQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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