SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6b08d154ca628561390f013524d928919d721afc84f26c4869a25de6e3b5195c' 
  AND token = 'dGgqJa1BLD/MGhRgNC+/bCig4svONuSME4/K/bsItow=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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