SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '27d796cd3b7f3635cd2a441e5ea602f148d81e10ec6434f5dc4497182fd70b68' 
  AND token = 'EIzS/IYdypF4hv1SWsEXVeL4t07arm9hfxEDNn+tLcQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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