SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0b48f0c1cf43599a273e2a2816f5f01080d957ea8bff9839daf2fcda2aa3875e' 
  AND token = '8dOLGFlb+UbljX7zsk9i8JDfELY2SoyUoEu6f5SrYzo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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